Header and menu button

Start with this Snippet:
https://www.themesandco.com/snippet/change-logo-social-icons-tagline-navbar-header/

Thank you, but i really am a newbie when it comes to CSS, ive looked around and i didn’t found what i am looking for.

I want the Navbar button to be centered, and the tagline too, i can do this by changing the left marges but then when i open the website with another computer that has a different screen they arent centered anymore ofcourse.

Anyone that can help me please?